It is generally accepted that there are two subsets of septo-optic dysplasia (deMorsier's syndrome), one with schizencephaly and the other without schizencephaly. A third form of the anomaly which is associated with callosal absence has also been described. Except for schizencephaly, the association of septo-optic dysplasia with another major type of disorder of neuronal migration and organization such as cortical dysplasia, has not yet been reported. We report the MR imaging examination of a 3-year-old patient with bilateral rolandic cortical dysplasia, and with apparent thinning of the optic nerves, and absent septum pellucidum (septo-optic dysplasia) as a new combination. This can be labelled as cortico-septo-optic dysplasia.